1. Field of the Invention
The present invention relates to an apparatus for and a method of constructing a concrete block mat under water, and more particularly to an apparatus for and a method of constructing a concrete block mat consisting of unit concrete blocks interlocked together in the form of a mat by way of connections for adjacent interlocking members of those unit concrete blocks.
2. Description of the Prior Art
Constructions installed under water at rivers or seashores to block the activity of water or for other purposes are subjected to erosion or scouring at their foundations due to.backslash.the force of flowing water or wave force. In order to avoid such an erosion phenomenon, a variety of methods have been proposed.
The most representative method is to spread ripraps having a desired size throughout an under water location where erosion or scouring may occur, thereby forming a riprap layer at the under water location. The riprap layer is then planarized to have a trapezoidal shape. However, this method has drawbacks in that the riprap layer may easily collapse, thereby easily failing in its desired function. In particular, the work for planarizing the surface of the riprap layer is typically carried out by divers or underwater robots. However, where the planarizing work is conducted by divers, it is greatly influenced by the weather conditions of nature. As a result, there are drawbacks such as a reduction in workability, high labor costs, a lack of safety, and degraded reliability. Where the planarizing work is conducted by underwater robots, there is no drawback involved in the case using divers. In this case, however, it is difficult for the underwater robots to cope with the topology of the ground under water and a variation in working conditions. Use of underwater robots also involves high costs.
Recently, a method using concrete blocks has also been proposed. In accordance with this method, concrete blocks having a desired weight are prepared. These concrete blocks are spread one by one throughout an under water location, where erosion or scouring may occur, using a crane. After being placed under water, those concrete blocks are interlocked together in the form of a mat. However, this method has a variety of problems. That is, the placement of concrete blocks under water should be achieved in such a fashion that an accurate relative positional relationship is maintained between adjacent ones of those concrete blocks. To this end, divers continuously communicate with operators manipulating a crane on the ground so as to individually install the concrete blocks at accurate positions under water. After installing all of the necessary concrete blocks, the divers should conduct a task of interlocking the concrete blocks together. For these reasons, there is a difficulty in conducting the installation of concrete blocks. As a result, there are drawbacks such as a reduction in workability, a lack of safety, and degraded reliability. Where concrete blocks are installed in such a fashion that they are interlocked together in the form of a mat, it is necessary to planarize the under water location where those concrete blocks are to be installed before the concrete blocks are spread throughout that location. However, this planarization work involves the same drawbacks as those involved in the installation of the riprap layer as mentioned above.